Tank structure of heat exchanger

ABSTRACT

In a tank structure of a heat exchanger having a narrow width header plate, to reduce thermal stress generated in a tube on the outermost side of the header plate in a lengthwise direction. Insertion holes, except for end-portion tube insertion holes at least located at end portions of a header plate in the lengthwise direction, are linked with deformation prevention beads formed along the lengthwise direction of the header plate, and the end-portion tube insertion holes are not linked with the deformation prevention beads.

TECHNICAL FIELD

The present invention relates to a tank structure of a heat exchangerthat is most suitable for radiators for engine cooling water, oilcoolers and other heat exchangers, and relates to one that improves heatdurability thereof.

BACKGROUND ART

As a conventional tank of a heat exchanger, there has been found one inwhich the width of a header plate is narrowed for weight saving andspace reduction.

In the tank of a heat exchanger in Patent Literature 1 below, a sealingsurface 24 of a header plate 4 a is formed in flat, as shown in FIG. 8B,to narrow the width of the header plate.

Further, between tube insertion holes formed in the header plate 4 a, adeformation prevention beads 7, for supporting a tank main body 6 andpreventing deformation of the tank main body 6 when the tank main body 6is caulked, is provided.

CITATION LIST Patent Literature

PTL 1: WO 2017/069280 A1

SUMMARY OF INVENTION Technical Problem

In the header plate 4 a described in the Patent Literature 1, a highburring 22 is formed on long side portions of respective tube insertionholes, and a low burring is formed on short side portions.

Then, a brazing joining line in the short side portion is located on atank outer side as compared with that in the long side portion.

As the result of the examination of the present inventor, it has beenfound that concentration of thermal stress generated due to unevennessof temperature distribution in the heat exchanger on the tube short sideportion became prominent in an instance where the brazing joining linein the short side portion was located on a tank outer side as comparedwith that in the long side portion as described above.

Meanwhile, the stress concentration is prominent in a tube at theend-portion in the lengthwise direction of the header plate 4 a.

Moreover, in an instance where a tank is divided into a plurality ofzones by partition portions and fluids having different temperatureseach other flow into respective zones, the stress concentration isprominent in tubes near the partition portions.

Therefore, the present invention is directed to relax the concentrationof thermal stress on a tube short side portion near a brazed portionbetween the tube and the header plate in a heat exchanger having aheader plate with narrow width.

Solution to Problem

The present invention according to a first aspect thereof is a tankstructure of a heat exchanger, including:

a header plate 4 having a plurality of flat tube insertion holes 3constituted of a pair of facing short side portions 1 and a pair of longside portions 2 linking the both short side portions 1;

a plurality of flat tubes 5 whose end-portions have been inserted intothe respective tube insertion holes 3, and the insertion portions havebeen brazed;

a tank main body 6 to which a rim of the header plate 4 is fixed bycaulking, and

the short side portions 1 of the plurality of tube insertion holes 3 arelocated in a width direction of the header plate 4, and their tubeinsertion holes 3 are arranged separately each other in a lengthwisedirection of the header plate 4, wherein

respective tube insertion holes 3, except for end-portion tube insertionholes 8 at least located at end-portions in the lengthwise direction,are linked by deformation prevention beads 7 formed along the lengthwisedirection of the header plate 4; and

the end-portion tube insertion holes 8 are not linked by the deformationprevention beads 7.

The present invention according to a second aspect thereof is the tankstructure of a heat exchanger according to the first aspect, wherein:

a low burring 9 having low height is formed on a hole brim of the shortside portions 1 of the respective tube insertion holes 3, while a highburring 10 higher than the low burring 9 is formed on the long sideportions 2 of the respective tube insertion holes 3 except for at leastthe end-portion tube insertion holes 8; and

the low burring 9 is formed on the hole brim of the end-portion tubeinsertion holes 8 throughout the entire circumference thereof.

The present invention according to the third aspect thereof is the tankstructure of a heat exchanger according to the first aspect, wherein:

the low burring 9 having low height is formed on a hole brim of theshort side portions 1 of the respective tube insertion holes 3, and thehigh burring 10 higher than the low burring 9 is formed on the long sideportions 2 of the respective tube insertion holes 3 except for at leastthe end-portion tube insertion holes 8; and

the low burring 9 is formed on hole brims of both end-portions of thelong side portions 2 of at least the end-portion tube insertion holes 8,and the high burring 10 is formed on a hole brim of the long sideportion 2 except for both end-portions thereof.

The present invention according to the fourth aspect thereof is a tankstructure of a heat exchanger, including:

a header plate 4 having a plurality of flat tube insertion holes 3constituted of a pair of facing short side portions 1 and a pair of longside portions 2 linking the both short side portions 1;

a plurality of flat tubes 5 whose end-portions have been inserted intothe respective tube insertion holes 3, and the insertion portions havebeen brazed; and

a tank main body 6 to which a rim of the header plate 4 is fixed bycaulking, in which

the short side portions 1 of the plurality of tube insertion holes 3 arelocated in a width direction of the header plate 4, and their tubeinsertion holes 3 are arranged separately each other in a lengthwisedirection of the header plate 4,

wherein:

the tank main body 6 harbors a partition portion 19 that divides thesame into a plurality of zones in a lengthwise direction;

a dummy tube insertion hole 11 is formed at the header plate 4 locatednear the partition portion 19, and the end-portion tube insertion hole 8with a plurality of tube insertion holes 3 in parallel on both sides ofthe dummy tube insertion hole 11;

flat tubes 5 are inserted into respective tube insertion holes 3, 8, 11;

respective tube insertion holes 3, except for the dummy tube insertionhole 11 and an end-portion tube insertion hole 8 located at least to thefirst from the dummy tube insertion hole 11, are linked by thedeformation prevention beads 7 formed along the lengthwise direction ofthe header plate 4; and

formed so that the deformation prevention beads 7 do not exist for thedummy tube insertion hole 11 and the end-portion tube insertion hole 8located at least to the first from the dummy tube insertion hole 11.

The present invention according to the fifth aspect thereof is the tankstructure of a heat exchanger according to the fourth aspect, wherein:

the low burring 9 is formed on short side portions 1 of the respectivetube insertion holes 3;

the high burring 10 is provided for the long side portions 2 of therespective tube insertion holes 3 except for the dummy tube insertionhole 11 and the end-portion tube insertion hole 8 located at least tothe first from the dummy tube insertion hole 11; and

the low burring 9 is provided for the end-portion tube insertion hole 8located at least to the first from the dummy tube insertion hole 11throughout the entire circumference thereof.

Advantageous Effects of Invention

The invention according to the first aspect is an invention, wherein:respective tube insertion holes 3, except for end-portion tube insertionholes 8 at least located at the end-portions of the header plate 4 inthe lengthwise direction, are linked by the deformation prevention beads7 formed along the lengthwise direction of the header plate 4, and thedeformation prevention beads 7 are not linked to the end-portion tubeinsertion hole 8.

As a result of eliminating the deformation prevention beads 7 from theend-portion tube insertion hole 8 as described above, flexural rigidityof the part of the header plate 4 is reduced, and deformation of thepart absorbs effectively thermal deformation due to thermal stressgenerated larger in the flat tube 5 that should be inserted into theend-portion. Moreover, when the rim of the header plate 4 is caulked andfixed to the tank main body 6, the caulking load is supported withdeformation prevention beads 7 provided for other tube insertion holes3. Therefore, the function of tank deformation prevention by thedeformation prevention beads 7 is ensured and, furthermore, thermalstress generated in the flat tube 5 inserted into the end-portion tubeinsertion hole 8 is reduced.

The invention according to the second aspect is an invention, wherein:the low burring 9 having low height is formed on the hole brim of theshort side portions 1 of respective tube insertion holes 3, while thehigh burring 10 higher than the low burring 9 is formed on the long sideportions 2 of respective tube insertion holes 3 except for theend-portion tube insertion hole 8, and the low burring 9 is formed onthe hole brim of the end-portion tube insertion holes 8 throughout theentire circumference of the hole brims.

Hereby, the brazing joining line of the end-portion tube insertion hole8 with the flat tube 5 in the short side portion 1 becomes the same asthat in the long side portion 2. Therefore, stress concentration on theflat tube 5 in the short side portion 1 is relaxed.

The invention according to the third aspect is an invention, wherein:the low burring 9 is formed on the hole brims of both end-portions ofthe long side portions 2 of the end-portion tube insertion holes 8,while the high burring 10 is formed on the hole brim of long sideportions 2 except for the both end-portions.

As a result of forming the high burring 10 on the long side portions 2,except for both end-portions thereof, of the end-portion tube insertionholes 8 in the same way as in other tube insertion holes 3 as describedabove, expansion workability for the flat tube 5 to be inserted therecan be made almost the same as that for flat tubes 5 in other sites.

Meanwhile, into an opening end-portion of flat tube 5 to be insertedinto each of insertion holes 3, 8, an expansion jig is inserted and theouter circumference thereof is enlarged, to thereby bring the outercircumference of the flat tube 5 into close contact with each ofinsertion holes 3, 8. In this condition, the flat tube 5 and the headerplate 4 are brazed.

Moreover, the low burring 9 has been formed on hole brims at bothend-portions of the long side portions 2 of the end-portion tubeinsertion hole 8, and therefore stress concentration on the flat tube 5at a joining portion with the short side portion 1 thereof is relaxed.

The invention according to the fourth aspect is an invention, wherein:the tank main body 6 harbors a partition portion 19 that divides thesame into a plurality of zones in a lengthwise direction; a dummy tubeinsertion hole 11 is formed at the header plate 4 located near thepartition portion 19, with the end-portion tube insertion hole 8 and aplurality of tube insertion holes 3 in parallel on both sides of thedummy tube insertion hole 11; respective tube insertion holes 3, exceptfor the dummy tube insertion hole 11 and an end-portion tube insertionhole 8 located at least to the first from the dummy tube insertion hole11, are linked by the deformation prevention beads 7 formed along thelengthwise direction of the header plate 4; and formed such that thedeformation prevention beads 7 do not exist for the dummy tube insertionhole 11 and the end-portion tube insertion hole 8 located at least tothe first from the dummy tube insertion hole 11.

Hereby, the flexural rigidity of the header plate 4 corresponding to thepart from which the deformation prevention beads 7 have been eliminatedis reduced and the part deforms, to thereby absorb deformation due tothermal stress generated in the flat tube 5 inserted there.

Moreover, when the rim of the header plate 4 is caulked and fixed to thetank main body 6, the load to be added is supported with deformationprevention beads 7 formed at other tube insertion holes 3. Therefore,the function of tank deformation prevention is ensured and, furthermore,thermal stress generated in the flat tube 5 inserted into theend-portion tube insertion hole 8 is reduced.

The invention according to the fifth aspect is an invention, wherein:the high burring 10 has been provided for long side portions 2 ofrespective tube insertion holes 3, except for the dummy tube insertionhole 11 and the end-portion tube insertion hole 8, and the low burring 9has been formed to the end-portion tube insertion hole 8 throughout theentire circumference thereof.

Hereby, the brazing joining line of the end-portion tube insertion hole8 with the flat tube 5 in the short side portion 1 becomes similar tothat in the long side portion 2. Therefore, stress concentration on theflat tube 5 in the short side portion 1 is relaxed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1A illustrates an exploded perspective view of a tank structure ofa heat exchanger in a first Example of the present invention, and FIG.1B illustrates a main part perspective view of a header plate 4 thereof.

FIG. 2A illustrates a plan view of the header plate 4 in the firstExample, FIG. 2B is a view seen along a B-B arrow in FIG. 2A, FIG. 2C isa view seen along a C-C arrow in FIG. 2A, FIG. 2D is a view seen along aD-D arrow in FIG. 2A, FIG. 2E is a perspective view of an end-portiontube insertion hole 8 seen from the underside of FIG. 2D, FIG. 2F is aview seen along an F-F arrow in FIG. 2A, and FIG. 2G is a perspectiveview seen from the underside of FIG. 2F.

FIG. 3 illustrates a perspective view of a header plate 4 of a tankstructure of a heat exchanger in a second Example of the presentinvention.

FIG. 4A illustrates a plan view of the header plate 4 in the secondExample, FIG. 4B—is a view seen along a B-B arrow in FIG. 4A, FIG. 4C isa view seen along a C-C arrow in FIG. 4A, FIG. 4D is a view seen along aD-D arrow in FIG. 4A, FIG. 4E is a perspective view of an end-portiontube insertion hole 8 seen from the underside of FIG. 4D, FIG. 4F is aview seen along an F-F arrow in FIG. 4A, and FIG. 4G is a perspectiveview seen from the underside of FIG. 4F.

FIG. 5 illustrates a front view of a tank structure of a heat exchangerin a third Example of the present invention.

FIG. 6A illustrates a main part plan view seen along a VI-VI arrow inFIG. 5, FIG. 6B is a cross-sectional view seen along a B-B arrow in FIG.6A, FIG. 6C is a view seen along a C-C arrow in FIG. 6A, and FIG. 6D isa view seen along a D-D arrow in FIG. 6A.

FIG. 7 illustrates a plan view of a tank structure of a heat exchangerin a fourth Example.

FIG. 8A illustrates a main part plan view of a tank structure of aconventional heat exchanger, FIG. 8B is a B-B cross-sectional view ofFIG. 8A, and FIG. 8C is a main part perspective view of the tankstructure.

DESCRIPTION OF EMBODIMENTS

Next, embodiments of the present invention will be explained on thebasis of the drawings, with Examples.

Heat exchangers in each of Examples explained below can be utilized as aradiator for cooling engine cooling water, a sub-radiator for coolingauxiliary machinery cooling water, or the like, as an example.

Example 1

FIG. 1 and FIG. 2 show the tank structure of the heat exchanger in thefirst Example of the present invention, in which FIG. 1A illustrates anexploded perspective view thereof, and FIG. 1B illustrates a perspectiveview of the header plate 4 for use in it. FIG. 2A illustrates a mainpart plan view of the header plate 4, and FIG. 2B to FIG. 2G illustratecross-sectional views and perspective views, respectively, in FIG. 2A.

This heat exchanger is a heat exchanger, in which a flat tube 5 and acorrugated fin 12 are arranged alternately in parallel to form a core,end-portions of the flat tubes 5 are inserted into tube insertion holes3 and end-portion tube insertion holes 8, respectively, provided for abottom face 41 of the header plate 4, and their insertion portions arebrazed and fixed.

Meanwhile, on both sides in the width direction of the core, a pair ofside plates 15 (that on the left side is omitted) are arranged.

Inner circumferences of respective tube insertion holes 3 and twoend-portion tube insertion holes 8 are formed slightly larger than anouter circumference of the flat tube 5 to be inserted there. When theflat tube 5 is inserted there later, an expansion jig is inserted intothe tip portion thereof to expand it due to plastic deformation, andeach hole brim of the tube insertion holes 3 and end-portion tubeinsertion holes 8 is brought into close contact with the end-portion ofthe flat tube 5.

Subsequently, the flat tube 5 and each of tube insertion holes 3 andend-portion tube insertion holes 8 are integrally brazed and fixed.

Next, a tank main body 6 is constituted of a synthetic resin material inthis Example, in which a small flange 6 a is formed on the outercircumference while tooth portions 6 b are integrally protruded atregular intervals on the inner circumference. Between each of the toothportions 6 b, a tube escape portion 6 c is formed, and marginal portionson a long axis side of tip portions of respective flat tubes 5 intrudeinto the tube escape portion. Further, a seal ring 13 is arrangedbetween the tooth portion 6 b and the inner surface of the tank mainbody 6.

Further, nail portions for caulking 16 provided at regular intervals forthe header plate 4 are caulked to the outer circumference of the smallflange 6 a of the tank main body 6, to thereby form the tank structureof the heat exchanger. Meanwhile, in FIG. 1, an underside tank structureis omitted, but the underside tank is formed in the same way.

The header plate 4 of this Example has been formed into a planarrectangle. In the bottom face 41 of the header plate 4, a plurality offlat tube insertion holes 3 constituted of a pair of facing short sideportions 1 and a pair of long side portions 2 linking both short sideportions 1 have been drilled at regular intervals. At both end-portionsin the lengthwise direction of the header plate 4 (in FIG. 1, FIG. 2A,the left side is omitted), in this Example, two end-portion tubeinsertion holes 8 constituted of a pair of short side portions 1 and apair of long side portions 2 have been drilled in the same way as thetube insertion hole 3.

The inner circumferences of respective tube insertion holes 3 andend-portion tube insertion holes 8 are identical.

As shown in FIG. 1 and FIG. 2A, FIG. 2F, FIG. 2G, respective tubeinsertion holes 3 are connected with a pair of parallel deformationprevention beads 7 protruding toward the inner face side of the tankmain body 6. However, in this Example, the deformation prevention beads7 are not linked to two end-portion tube insertion holes 8.

Hereby, the surrounding of two end-portion tube insertion holes 8 isformed with the rigidity weaker than that in the surrounding of othertube insertion holes 3.

Moreover, in this Example, a burring protruding toward the inner faceside of the tank main body 6 has been formed on hole brims of respectivetube insertion holes 3 and end-portion tube insertion holes 8.

As shown in FIG. 2B, the high burring 10 having high height from thebottom face 41 of the header plate 4 to the tip of the burring has beenformed on hole brims of a pair of long side portions 2 of respectivetube insertion holes 3. Then, as shown in FIG. 2C, the low burring 9having lower height than the high burring 10 has been formed on holebrims of a pair of short side portions 1 of respective tube insertionholes 3.

Further, the low burring 9 and the high burring 10 are connectedsmoothly.

Moreover, as shown in FIG. 2B and FIG. 2C, the low burring 9 havinglower height than the high burring 10 has been formed on the hole brimof the end-portion tube insertion hole 8, and the height of the lowburring 9 is kept at an approximately the same throughout the entirecircumference of the end-portion tube insertion hole 8.

Hereby, the brazing joining line of the end-portion tube insertion hole8 with the flat tube 5 in the short side portion 1 becomes similar tothat in the long side portion 2, and therefore stress concentration onthe flat tube 5 in this short side portion 1 is relaxed.

Example 2

Next, FIG. 3 and FIG. 4 show a second Example of the present invention.This Example is different from the first Example in the shape of aburring at the hole brim portions of two end-portion tube insertionholes 8 provided on both end-portions in the lengthwise direction of theheader plate 4.

In this Example, as shown in FIG. 3 and FIG. 4C, the low burring 9 hasbeen formed on hole brims of both end-portions in the long side portion2 of the end-portion tube insertion hole 8, and, as shown in FIG. 3 andFIG. 4B, the high burring 10 has been formed on the hole brim of thelong side portion 2 except for the both end-portions.

As a result of setting the same high burring 10 as that of other tubeinsertion holes 3 on the long side portion 2 of the end-portion tubeinsertion hole 8 except for both end-portions thereof as describedabove, the expansion workability of the flat tube 5 to be inserted therecan be made almost the same as that of other flat tubes 5.

Moreover, on hole brims of both end-portions of the long side portion 2of the end-portion tube insertion hole 8, the low burring 9 has beenformed, and therefore stress concentration on the flat tube 5 at thejoining portion with the short side portion 1 thereof is relaxed.

Example 3

Next, FIG. 5 and FIG. 6 show a third Example of the present invention,in which FIG. 5 is a front view thereof, FIG. 6A is a view seen along aVI-VI arrow in FIG. 5, FIG. 6B is a view seen along a B-B arrow in FIG.6A, FIG. 6C is a view seen along a C-C arrow in FIG. 6A, and FIG. 6D isa view seen along a D-D arrow in FIG. 6A.

In this tank structure of a heat exchanger, in FIG. 5, upper and lowertanks constituted of a tank main body 6 and the header plate 4 have, viavalley portions provided at a middle in the lengthwise direction, afirst tank portion 17 and a second tank portion 18 on both sidesthereof.

In the inside of the tank main body 6, as shown in FIG. 6B, a pair ofpartition portions 19 dividing the inside of the tank in the lengthwisedirection into a plurality of zones are arranged facing each other, andend-portions thereof are joined with the inner surface of the headerplate 4 via annular sealing rings 13 respectively. As shown in FIG. 6A,FIG. 6B, to this header plate 4, the dummy tube insertion hole 11 hasbeen formed at a position corresponding to the vicinity of the partitionportion 19, and, while sandwiching the dummy tube insertion hole 11,end-portion tube insertion holes 8 and tube insertion holes 3 arearranged one by one in a line. Further, the end-portion of the flat tube5 has been inserted into each of insertion holes 3, 8, 11, and the flattube 5 and each of insertion portions are brazed and fixed.

In this way, on both sides in the lengthwise direction of the dummy tubeinsertion hole 11, a first flow path 20 and a second flow path 21 eachconstituted of an assembly of a plurality of the flat tubes 5 arearranged, and different heat media circulate through these flow paths.As an example, engine cooling water may be made to circulate through thefirst flow path 20, and auxiliary machinery cooling water may be made tocirculate through the second flow path 21.

Here, the dummy tube insertion hole 11, and the end-portion tubeinsertion hole 8 located to the first from the dummy tube insertion hole11 are formed so that a deformation prevention beads 7 do not exist, asshown in FIG. 6A.

Further, on the hole brim portion of each tube insertion hole 3, thehigh burring 10 has been formed on the long side portion 2 thereof, andthe low burring 9 (not shown) has been formed on the short side portion1. Moreover, on hole brim portions of the end-portion tube insertionholes 8, the low burring 9 has been formed, respectively.

As such, the rim of the hole brim portion of the end-portion tubeinsertion hole 8 and the rim portion of the dummy tube insertion hole 11are formed with the rigidity weaker than the rigidity of others, tothereby absorb stress generated in the flat tube 5 inserted into thedummy tube insertion hole 11 and the end-portion tube insertion hole 8.

Furthermore, the brazing joining line of the end-portion tube insertionhole 8 with the flat tube 5 in the short side portion 1 becomes similarto that in the long side portion 2, and therefore stress concentrationon the flat tube 5 in the short side portion 1 is relaxed.

Example 4

Next, FIG. 7 is a plan view of a header plate 4 in a fourth Example ofthe present invention. This invention is different from the invention inthird Example in that three end-portion tube insertion holes 8 have beenformed, respectively, while neighboring both sides of the dummy tubeinsertion hole 11.

Thereby, stress concentration on the flat tube 5 in the short sideportion 1 of the end-portion tube insertion hole 8 is even more relaxed.

REFERENCE SIGNS LIST

-   1: short side portion-   2: long side portion-   3: tube insertion hole-   4: header plate-   4 a: header plate-   5: flat tube-   6: tank main body-   6 a: small flange-   6 b: tooth portion-   6 c: tube escape portion-   7: deformation prevention bead-   8: end-portion tube insertion hole-   9: low burring-   10: high burring-   11: dummy tube insertion hole-   12: corrugated fin-   13: seal ring-   14: tooth portion-   15: side plate-   16: nail portion for caulking-   17: first tank portion-   18: second tank portion-   19: partition portion-   20: first flow path-   21: second flow path-   22: burring-   22 a: R portion-   24: sealing surface-   41: bottom face

1. A tank structure of a heat exchanger, comprising: a header platehaving a plurality of flat tube insertion holes constituted of a pair offacing short side portions and a pair of long side portions linking theboth short side portions; a plurality of flat tubes whose end-portionshave been inserted into the respective tube insertion holes, and theinsertion portions have been brazed; a tank main body to which a rim ofthe header plate is fixed by caulking, and the short side portions ofthe plurality of tube insertion holes are located in a width directionof the header plate, and their tube insertion holes are arrangedseparately each other in a lengthwise direction of the header plate,wherein: respective tube insertion holes, except for end-portion tubeinsertion holes at least located at end-portions in the lengthwisedirection, are linked by deformation prevention beads formed along thelengthwise direction of the header plate; and the end-portion tubeinsertion holes are not linked by the deformation prevention beads. 2.The tank structure of a heat exchanger according to claim 1, wherein: alow burring having low height is formed on a hole brim of the short sideportions of the respective tube insertion holes, while a high burringhigher than the low burring is formed on the long side portions of therespective tube insertion holes except for at least the end-portion tubeinsertion holes; and the low burring is formed on the hole brim of theend-portion tube insertion holes throughout the entire circumferencethereof.
 3. The tank structure of a heat exchanger according to claim 1,wherein: the low burring having low height is formed on a hole brim ofthe short side portions of the respective tube insertion holes, and thehigh burring higher than the low burring is formed on the long sideportions of the respective tube insertion holes except for at least theend-portion tube insertion holes; and the low burring is formed on holebrims of both end-portions of the long side portions of at least theend-portion tube insertion holes, and the high burring is formed on ahole brim of the long side portion except for both end-portions thereof.4. A tank structure of a heat exchanger, including: a header platehaving a plurality of flat tube insertion holes constituted of a pair offacing short side portions and a pair of long side portions linking theboth short side portions; a plurality of flat tubes whose end-portionshave been inserted into the respective tube insertion holes, and theinsertion portions have been brazed; and a tank main body to which a rimof the header plate is fixed by caulking, in which the short sideportions of the plurality of tube insertion holes are located in a widthdirection of the header plate, and their tube insertion holes arearranged separately each other in a lengthwise direction of the headerplate, wherein: the tank main body harbors a partition portion thatdivides the same into a plurality of zones in a lengthwise direction; adummy tube insertion hole is formed at the header plate located near thepartition portion, and the end-portion tube insertion hole with aplurality of tube insertion holes in parallel on both sides of the dummytube insertion hole; flat tubes are inserted into respective tubeinsertion holes; respective tube insertion holes, except for the dummytube insertion hole and an end-portion tube insertion hole located atleast to the first from the dummy tube insertion hole, are linked by thedeformation prevention beads formed along the lengthwise direction ofthe header plate; and formed so that the deformation prevention beads donot exist for the dummy tube insertion hole and the end-portion tubeinsertion hole located at least to the first from the dummy tubeinsertion hole.
 5. The tank structure of a heat exchanger according toclaim 4, wherein: the low burring is formed on short side portions ofthe respective tube insertion holes; the high burring is provided forthe long side portions of the respective tube insertion holes except forthe dummy tube insertion hole and the end-portion tube insertion holelocated at least to the first from the dummy tube insertion hole; andthe low burring is provided for the end-portion tube insertion holelocated at least to the first from the dummy tube insertion holethroughout the entire circumference thereof.